Phytosterols and γ-Oryzanol as Cholesterol Solid Phase Modifiers during Digestion

Literature reports that ingestion of phytosterols and γ-oryzanol contributes to cholesterol lowering. Despite in vivo observations, thermodynamic phase equilibria could explain phenomena occurring during digestion leading to such effects. To advance the observations made by previous literature, this study was aimed at describing the complete solid-liquid phase equilibrium diagrams of cholesterol + phytosterol and γ-oryzanol systems by DSC, evaluating them by powder X-ray, microscopy, and thermodynamic modeling. Additionally, this study evaluated the phenomena observed by an in vitro digestibility method. Results confirmed the formation of solid solution in the cholesterol + phytosterols system at any concentration and that cholesterol + γ-oryzanol mixtures formed stable liquid crystalline phases with a significant melting temperature depression. The in vitro protocol supported the idea that the same phenomena can occur during digestion in which mechanochemical forces were probably the mechanisms promoting cholesterol solid phase changes in the presence of such phytocompounds. In this case, these changes could alter cholesterol solubility and possibly its absorption in the gastrointestinal lumen.

A Simple, Rapid, and Reliable Titrimetric Method for the Determination of Glycerol at Low Concentration

Glycerol can be determined in several products by various analytical techniques. Titrimetric ones have stood out for their low cost, being recommended as standards. However, reliable, simple, fast, and green methods with low quantification limits are still needed. Titration of glycerol is based on its oxidation by periodate (Malaprade reaction) producing formic acid, formic aldehyde, and iodate. Iodate and periodate are iodometrically titrated, but mutual interference between these ions has produced methods with some drawbacks. Here is proposed to mask periodate with molybdate, to eliminate interference, determining the glycerol content through iodate, employing iodometric titration. Solutions containing from 10 to 1000 μg of glycerol were analyzed (error < 3.4%). The method was successfully applied for the determination of glycerol in biodiesels from different raw materials. Recoveries were from 92.9 ± 0.4 to 111 ± 3%. Semi-micro extraction was done, providing a fast procedure for determining free glycerol in biodiesel (< 10 min).

Rifle bullets comparison by wavelength dispersive X-ray fluorescence spectroscopy and chemometric analysis

Despite Federal Bureau of Investigation Laboratory announcing the discontinuation of bullet lead examinations, knowledge of the composition of the bullets has been used as an alternative means of identifying their origin, achieving success in some case studies. In this work, wavelength dispersion X-ray fluorescence (WDXRF) and chemometrics were used for the analysis of rifle bullets, in order to identify the spectral similarities of these samples. For this purpose, 54 lead core fragments from 7.62 mm rifle bullets from 5 different manufacturers were obtained: Companhia Brasileira de Cartuchos (CBC), Israel Military Industries (IMI), Federal Cartridge (FC), Fray Luiz Beltrán (FLB) and Zavod Vlasim (ZV). Principal components analysis (PCA) discriminated the five groups of bullets according to their manufacturers in a three-dimensional scores graph, where 3 principal components accounted for>99% of the variability between the samples. The spectral region for Sb and the scattering region together proved to be determinant for discrimination of the groups. The dendrogram presented in the hierarchical cluster analysis (HCA) showed the formation of five groups. The k-nearest neighbor algorithm (k-NN) and soft independent modeling of class analogy (SIMCA) correctly classified all samples of the test set. X-ray scattering spectrum were used for the first time in the analysis of the fragments and contributed to the grouping of samples from the same manufacturers. The results indicate that the WDXRF technique is suitable for forensic purposes in case studies, as, besides being quick and relatively simple, it has the advantage of preserving evidence.

Bacteriophage-Based Biosensing of Pseudomonas aeruginosa: An Integrated Approach for the Putative Real-Time Detection of Multi-Drug-Resistant Strains

During the last decennium, it has become widely accepted that ubiquitous bacterial viruses, or bacteriophages, exert enormous influences on our planet’s biosphere, killing between 4–50% of the daily produced bacteria and constituting the largest genetic diversity pool on our planet. Currently, bacterial infections linked to healthcare services are widespread, which, when associated with the increasing surge of antibiotic-resistant microorganisms, play a major role in patient morbidity and mortality. In this scenario, Pseudomonas aeruginosa alone is responsible for ca. 13–15% of all hospital-acquired infections. The pathogen P. aeruginosa is an opportunistic one, being endowed with metabolic versatility and high (both intrinsic and acquired) resistance to antibiotics. Bacteriophages (or phages) have been recognized as a tool with high potential for the detection of bacterial infections since these metabolically inert entities specifically attach to, and lyse, bacterial host cells, thus, allowing confirmation of the presence of viable cells. In the research effort described herein, three different phages with broad lytic spectrum capable of infecting P. aeruginosa were isolated from environmental sources. The isolated phages were elected on the basis of their ability to form clear and distinctive plaques, which is a hallmark characteristic of virulent phages. Next, their structural and functional stabilization was achieved via entrapment within the matrix of porous alginate, biopolymeric, and bio-reactive, chromogenic hydrogels aiming at their use as sensitive matrices producing both color changes and/or light emissions evolving from a reaction with (released) cytoplasmic moieties, as a bio-detection kit for P. aeruginosa cells. Full physicochemical and biological characterization of the isolated bacteriophages was the subject of a previous research paper.

Response Factor in GC-FID Methyl Ester Analysis in Several Biodiesels: A Comparative Study of the EN 14103:2011 and ABNT 15764:2015 Methods versus a Proposed GC-FID Procedure for Individual Ester Determination

A gas chromatography method with a flame ionization detector enabled by relative response factor was developed to determine the individual and the total content of esters in biodiesel. This method accounts for different response factors of the detector for a homologous series of esters that may be present in biodiesel. In this way, the determination of the total ester content of a reference sample (100.5%) was done with more accuracy by the proposed procedure (100.2%) than by official analytical methods: EN (74.68%) and ABNT (118.2%). Another advantage of the developed method is the possibility of determining individual ester concentrations, which provides information on several important biodiesel properties such as oxidative stability and cold flow properties. The mean absolute error in the determination of the individual ester content was ca. 1.1%.

Transdermal permeation of bacteriophage particles by choline oleate: potential for treatment of soft-tissue infections

Aim: A sodium alginate-based biohydrogel was prepared integrating choline oleate deep euthetic solvent as facilitator of transdermal delivery and a cocktail of lytic bacteriophages for Acinetobacter baumannii, aiming at treating soft-tissue infections by the aforementioned pathogen. Materials & methods: Two bacteriophages were isolated from a hospital sewage and a wastewater treatment plant sewage in Sorocaba (Brazil), and characterized via SDS-PAGE electrophoresis, transmission electron microscope and evaluation of lytic spectra of the bacteriophage cocktail. The biohydrogel was prepared and characterized by DSC, FTIR, XRD, DESEM, XRT and transdermal permeation of the bacteriophage cocktail. Results & conclusion: The physico-chemical characterization of the biohydrogel produce indicated adequate structural characteristics and ability to promote/facilitate transdermal delivery of bacteriophage particles, thus showing potential for biopharmaceutical applications.

Non-invasive Transdermal Delivery of Human Insulin Using Ionic Liquids: In vitro Studies

In this research project, synthesis and characterization of ionic liquids and their subsequent utilization as facilitators of transdermal delivery of human insulin was pursued. Choline geranate and choline oleate ionic liquids (and their deep eutectic solvents) were produced and characterized by nuclear magnetic resonance (¹H NMR), water content, oxidative stability, cytotoxicity and genotoxicity assays, and ability to promote transdermal protein permeation. The results gathered clearly suggest that all ionic liquids were able to promote/facilitate transdermal permeation of insulin, although to various extents. In particular, choline geranate 1:2 combined with its virtually nil cyto- and geno-toxicity was chosen to be incorporated in a biopolymeric formulation making it a suitable facilitator aiming at transdermal delivery of insulin.

Gravimetric Method for the Determination of Diclofenac in Pharmaceutical Preparations

A gravimetric method for the determination of diclofenac in pharmaceutical preparations was developed. Diclofenac is precipitated from aqueous solution with copper(II) acetate in pH 5.3 (acetic acid/acetate buffer). Sample aliquots had approximately the same quantity of the drug content in tablets (50 mg) or in ampules (75 mg). The observed standard deviation was about ± 2 mg; therefore, the relative standard deviation (RSD) was approximately 4% for tablet and 3% for ampule preparations. The results were compared with those obtained with the liquid chromatography method recommended in the United States Pharmacopoeia using the statistical Student's t-test. Complete agreement was observed. It is possible to obtain more precise results using higher aliquots, for example 200 mg, in which case the RSD falls to 1%. This gravimetric method, contrary to what is expected for this kind of procedure, is relatively fast and simple to perform. The main advantage is the absolute character of the gravimetric analysis.

Determination of Salicylate in Blood Serum by Flow Injection with Immobilized Salicylate Hydroxylase

A flow injection (FI) enzymatic system, based on the use of immobilized salicylate hydroxylase in glass beads, was developed for the determination of salicylate. Salicylate hydroxylase and nicotinamide adenine dinucleotide (NADH) are used to convert salicylate to catechol. The reaction of catechol with 4-aminophenol at high pH yields a colored product which is detected spectrophotometrically at 565 nm. Ten samples of human serum containing from 5.0 × 10−4 to 5.0 × 10−3 mol/L added salicylate were analyzed and the recovery was determined. Eight additional serum samples containing salicylate were analyzed by the Trinder test and the proposed method. The results obtained with the 2 methods showed good agreement by the statistical Student's t-test. The relative precision of the method is about 3.4% (RSD of the mean recovery). Considering the lowest concentration analyzed, the quantitative limit of detection is about 0.2 × 10−5 mol/L (3 × SD). The volume of the sample used was 150 μL. The proposed method was also used to analyze medicines containing acetylsalicylic acid. The results were statistically compared with those obtained through the U.S. Pharmacopoeia procedure and showed excellent agreement.

Phase behavior of cholesterol in mixtures with hypo- and hypercholesterolemic lipids

Some lipidic bioactives are largely reported to present hypocholesterolemic effects, for example, oleic acid, α-tocopherol, and octacosanol, found in rice-bran, olive, and sunflower oils. In contrast, some saturated and trans-unsaturated lipids found in animal fats or partially hydrogenated oils have been associated with the opposite effect. However, the mechanisms in which these lipids act for lowering or increasing cholesterol are not fully understood. In this context, this work was aimed at a fundamental physicochemical comprehension of how cholesterol phase behavior is affected in mixtures with these compounds. The complete solid-liquid equilibrium (SLE) phase diagrams of these mixtures were depicted by differential scanning calorimetry and microscopy, and also evaluated by the SLE thermodynamic theory. The minimal melting temperature (eutectic points) of the mixtures followed the order: α-tocopherol < oleic acid < elaidic acid < stearic acid < octacosanol. Among all biocompounds, stearic and trans-oleic acids promoted few changes in the normal thermodynamic behavior of cholesterol when in a mixture. In contrast, α-tocopherol induced a significant temperature depression in the system. Furthermore, at high concentrations of cholesterol (>90% molar fraction), the formation of solid solution was observed in all other systems, to a higher degree for oleic acid. The higher interactions of these beneficial compounds and the formation of solid solution that literature associates with the alteration of cholesterol enteric absorption probably correlates with their hypocholesterolemic effects.

First Time Determination of Important Catalyst Sodium Methoxide Used in Biodiesel by Colorimetric Method

A simple and selective spectrophotometric method has been developed for the first time for the determination of sodium methoxide in methanol solution in the presence of sodium hydroxide. The developed method involves the formation of a pink species by the reaction between sodium methoxide and α-santonin. The pink compound formed shows absorbance maximum at 513 nm. N, N-Dimethylformamide and methanol were used as solvents, and the reaction was performed at different temperatures and 25 °C was selected for further experiments. The pink compound formed was dried and then was studied using FTIR and mass spectrometry. The calibration curve was constructed from 0.10 to 0.30% (m/v) sodium methoxide in methanol, and the standard deviation is 0.010%. Similarly, the relative standard deviations of 28%, 26%, and 24% solutions of sodium methoxide were obtained in the range of 0.4 to 1.9%. The correlation coefficient of the analytical curve r = 0.9997; the limit of detection, LOD, is ca. 1.1 × 10^-3 % w/w; and the limit of quantification, LOQ, is ca. 3.2 × 10^-3 % w/w. The results of analysis were validated statistically.

GREEN AND SIMPLE UV-VISIBLE DIFFUSE REFLECTANCE AND TRANSMITTANCE METHODS FOR THE DETERMINATION OF NITROFURANTOIN IN PHARMACEUTICAL PREPARATIONS

Two quantitative analytical methods for the determination of nitrofurantoin in pharmaceutical preparations in the visible-ultraviolet range of the spectrum are reported. One of them uses the diffuse reflectance technique and the other transmittance measurements in aqueous solution. Both procedures are very simple to be performed and also present green characteristics as only polyethylene glycol and water are used as solvents. Commercial pharmaceutical preparations of the drug were analyzed using the proposed methods. The results were compared with those obtained when the HPLC procedure recommended by the USP was applied. Statistical comparison using the paired Student’s t test and the Snedecor’s F test showed good agreement between all the methods.

Microgravimetric method for the determination of metformin in pharmaceutical preparations and in the bulk drug

This article reports a microgravimetric method for the quantitative determination of metformin in bulk and in pharmaceutical preparations. The analysis is simple and relatively rapid. A complete analysis can be performed in only an hour and thirty minutes due to the drying procedure of the precipitate. However a sample can be treated every each five minutes. The method is based on the reaction of nickel (II) with metformin that in basic medium forms an orange precipitate. The reaction is performed in a plastic syringe. The filtration was done in a glass tube containing a sintered glass disk or in Millipore® syringe filters, with posterior weighing after drying. The analytical results were statistically compared with that obtained with a HPLC and with the titrimetric method suggested by the United States and by the Japanese pharmacopoeias.

Development and application of a portable instrument for drugs analysis in pharmaceutical preparations

This article describes the application and performance of an inexpensive, simple and portable device for colorimetric quantitative determination of drugs in pharmaceutical preparations. The sensor is a light detector resistor (LDR) incorporated into a black PTFE cell and coupled to a low-cost multimeter (Ohmmeter). Quantitative studies were performed with captopril/p-chloranil/H2O2 and methyldopa/ammonium molybdate systems. Calibration curves were obtained by plotting the electrical resistance of the LDR against the concentration of the colored species in the ranges 1.84 × 10-4 to 1.29 × 10-3mol L-1 and 5.04 × 10-4 to 2.52 × 10-3 mol L-1 for captopril/p-chloranil/H2O2 and methyldopa/ammonium molybdate systems, respectively, exhibiting good coefficients of determination. Statistical analysis of the results obtained showed no significant difference between the proposed methodologies and the official reported methods, as evidenced by the t-test and variance ratio at a 95% confidence level. The results of this study demonstrate the applicability of the instrument for simple, accurate, precise, fast,in situ and low-cost colorimetric analysis of drugs in pharmaceutical products.

Development and characterization of a hydrogel containing silver sulfadiazine for antimicrobial topical applications

Development and optimization of a hydrogel with impregnated silver sulfadiazine was pursued, for antimicrobial topical applications. The selected hydrogel exhibited a homogeneous appearance, with whitish colloration and devoid of any fractures or cracks. The content in impregnated silver sulfadiazine was within established limits (1%, w/w) with a standard deviation of up to 1.28%. The hydrogel presented a good characteristic in relation to release of the active antimicrobial principle, verified through swelling tests and antimicrobial activity. The swelling tests indicated a higher increase in weight during the first 6 h of contact with a moist environment, with a maximum value of 266.00 ± 0.81, and with maintenance of the original shape of the hydrogel. The impregnated silver sulfadiazine presented antimicrobial activity, as expected, indicating a prolonged release of the drug. The infrared spectra of the hydrogel with impregnated silver sulfadiazine indicated that the drug did not engage in any bonds with the polymeric matrix, which otherwise could have reduced its antimicrobial activity. The mechanical resistance tests produced good results, indicating that the hydrogels may be utilized in different locations of the human body with skin lesions.

Carbohydrate hydrogels with stabilized phage particles for bacterial biosensing: bacterium diffusion studies

Bacteriophage particles have been reported as potentially useful in the development of diagnosis tools for pathogenic bacteria as they specifically recognize and lyse bacterial isolates thus confirming the presence of viable cells. One of the most representative microorganisms associated with health care services is the bacterium Pseudomonas aeruginosa, which alone is responsible for nearly 15% of all nosocomial infections. In this context, structural and functional stabilization of phage particles within biopolymeric hydrogels, aiming at producing cheap (chromogenic) bacterial biosensing devices, has been the goal of a previous research effort. For this, a detailed knowledge of the bacterial diffusion profile into the hydrogel core, where the phage particles lie, is of utmost importance. In the present research effort, the bacterial diffusion process into the biopolymeric hydrogel core was mathematically described and the theoretical simulations duly compared with experimental results, allowing determination of the effective diffusion coefficients of P. aeruginosa in the agar and calcium alginate hydrogels tested.

Structural and functional stabilization of phage particles in carbohydrate matrices for bacterial biosensing

Infections associated with health care services are nowadays widespread and, associated to the progressive emergence of microorganisms resistant to conventional chemical antibiotics, are major causes of morbidity and mortality. One of the most representative microorganisms in this scenario is the bacterium Pseudomonas aeruginosa, which alone is responsible for ca. 13-15% of all nosocomial infections. Bacteriophages have been reported as a potentially useful tool in the diagnosis of bacterial diseases, since they specifically recognize and lyse bacterial isolates thus confirming the presence of viable cells. In the present research effort, immobilization of these biological (although metabolically inert) entities was achieved via entrapment within (optimized) porous (bio)polymeric matrices of alginate and agar, aiming at their full structural and functional stabilization. Such phage-impregnated polymeric matrices are intended for future use as chromogenic hydrogels sensitive to color changes evolving from reaction with (released) intracytoplasmatic moieties, as a detection kit for P. aeruginosa cells.